Phase responsive apparatus



Oct. .28, 1947. R. D. may

PHASE RESPONS IVE APPARATUS Filed May 25, 1943 2 Sheets-Sheet 2 MAMAl/VPl/ T SIGNAL v v v REFERENCE v0 TAG: i

s we 3m am BY MCCOY ATTORNEY Patented ct.

Rawley :D McCoy, Bronxvi-lle, N. assi'gnor -to Sperry Gyroscope Company,Inc., acorporation 'ofN'ew York kppiication May 25; 1943 Serial- No.48853913 Other "and further objects and advantages will becomev apparentas the description proceeds.

In. carrying out invention in its preferred;- form,'I utilize a pair(if-input transformers "which may be energized? by analternating-current or voltage "signal input and a, reference input, respectively.. One of the. transformers, for enample the transformersenergized. by the signal, input; has a center-tapped secondary winding:and has a 'pair'of electric "discharge devices, such. as triodes,connected inrseries across. its secondary-mnding with: one pair o'flikeelectrodes connected togetherto rem a junction terminal; Outputterminals of the" circuit are connected'to' the center tap "of the.transformer secondary winding'and tothe" junction terminal of tli'e triLode-vacuum tubes. Preferably, a second pair. of triodes is-alsoconnectedin.'series across the signnal transformersecondarywinding,,buteach'withv opposite polarity compared with. the Ifirstpairoi triodes. The reference voltage transformerprovided"withffour' windings Jeach of which-is. 3'5

connected-in the"grid 'circuit'Ora-different one or the triode-VacuumLtubes; "One of the windings maygalsobe-used as 'a'primary' winding,connected to the 'referencevmtagei' source.

A'loetterunderstanding of'the'invention will'be 4oafiorded floy the"following; detailed? description considered in' connection-with theaccompanying drawings, and-"those ifeatures of the invention whicharebelieved tocbe novelandipatentable will be pointedout in-theciaimsappen'ded hereto.

In the drawings, 7 v

Fig: 1*i's' a circuit diagram of one embodimen'tiv of my invention; I c7 p I Fig; 2 l is a circuitfiiagramof' anotherv embodimerit of-imyinvention; especially adapted for use with aeearemwave referencevoltage;

Fig; 3-" is a =-circ' ui t diagram of a; modification "of thearrangement of Fig; 2 avoidingjithe use of bias batteries; I

- pair of input, terminals 1-6.

,2' an input signa'lrwhicnmaytie applied to the apparatusandzshowingitwoz opposite] phase relationships;

. Figs-Sis ajgraphiillus-trating the waveform of. a reference:voltagevwhich may be used in conneotion withr-the-apparatusz ofvFigs; 2andVB; and

Fig, 6; is algraph-illustrating'thewaveshape of the: output =voltageobtained fromthe apparatus of Figs; 2-and 3; and showing; thee-fleet onthe; output voltage-oi the reversal of phase i11ust-rat-- dim i t vLike-referencecharacters are' utilizedthroughout-the;drawingstodesignatelike parts.

In the apparatus-illustrated in Fig. 1 there is ai pair of inputtransformers ;-and I2. The: transformer -l-l has-aepr-imarywinding I3con-- nected to/a pair of- -input terminals I l,v and the transformer12: has a winding l fi connected toa One pair of input terminals, for.examplethe-pairof terminals I6, is: adapted to be: connected to a sourceof referencevoltage and/theother pairrof input termirials, in this casethe: pair. of terminals M, is-

adapted. to. be .connected to .a source of signal voltage which is tobe. compared in phase with: the reference voltage. it will be understoodthat;

the reference voltage will have the. anticipated frequencyoft'he.si'g'nal'voltago.v V c The transformer flilv has two secondarywindings inse'ries or a single secondary winding I with an. intermediatetap,,pr eferab1y a center tap.'l 8 andendfterminals rlSt and"2]. A pairofcllrrent-controllingflevices 22 and 23, of the type having. voltageresponsive-. control: elements, is connected in ser-ies across thesecondary Winding: IT. A secondpair-ot current-controlling devices 24and li'i's also connecteddna series-between the transformer.enditer'minals l 9 and}! 'Th'e current-controllingdeViCesZZ to -2 5,inclusive, may takei'tnefform of electric discharge devices, 'sucnas.tribde vacuum tubes for example. The devices '22 ans; 23f mayconstitute unit's of' a twin triode vacuumetuhehaving'a common en-'veio'pe; and likewise the devices? 2-11 and 25 may, constitute unitsofa. second twin triode.

Theunits'ZTand.23"compriseflpositiveelectrodes. or anodes 26" and' 'lTconnected 7 to transformer end terminals l9: and .zll negativerelectrodes or cathodesjfli and 29l'connected together and to a junctionterminalfil H, andv control electrodes or rids 3Z and' '33 It willbe-observed that the current controlling devices. and 23: are. connectedin opposing. relation; that is, withone pair of like electrodes orelectrodes-of thersa-me' --Fig,: mgrgra h-illustratingthrrwaveiorm of5"5"'po'1arity'connectetil'together. The devices 24 and 25 are alsoconnected in opposed relation with one pair of like electrodes connectedtogether, but they are each connected to the transformer Winding l! inrelation opposite to the relation of the units 22 and 23.

Thus, the devices 24 and 25 have cathodes 34 and 35 connected to thetransformer end terminals i9 and 2! and anodes 36 and 31 connectedtogether and to a junction terminal 38. The two junction terminals 3|and 38 are connected to an output terminal 39 and the transformer centertap I3 is connected to a second output termina1 4 I.

The transformer I2 comprises, in addition to the winding l5, three otherwindings 42, 43 and 44. For the sake of compactness, the transformer I2is arranged as a semi-autotransformer with the winding 15 serving bothas a primary winding and as one of the secondary windings. It will beunderstood, however, that if a separate primary Winding is employed itwill be connected to the reference voltage input terminals [6, and thatan additional secondary winding will be provided for connection to thegrid 32 and the cathode 28 of the triode 22. The Winding 42 is connectedto the cathode 29 and the grid 33 of the triode 23. The windings 43 and44 are connectedv in the grid circuits of the triodes 24 and 25,respectively.

The transformer I2 is so wound that the upper ends of the windings i and42 and the lower ends of the windings 43 and 44 have the same relativepolarity at any given instant. For example, at the instant when the gridend of the winding l5 has positive polarity, the grid end of the Winding42 has negative polarity, as indicated by the plus and minus signs. Withrespect to the grids 32 and 33, the windings l5 and 42 may be spoken ofas having opposite relative polarities. Likewise, at the same instantthe grid end of the winding 43 has positive polarity and the grid end ofthe winding 44 has negative polarity. For the sake of illustration itmay be assumed that at the same instant at which the grids have thepolarities just designated, the instantaneous polarity of.

the signal voltage is such that the anode 26 and the cathode 34 havepositive polarity voltage applied thereto, and the anode 21 andcathode'35 have negative polarity voltage applied thereto.

Owing to the manner in which the windings and triodes are connected, atany given instant maximum current will flow in one but not in all of thetriodes 22, 23, 24 and 25. For example, with the instantaneouspolarities assumed and indicated by the plus and minus signs, the anode26 and the grid 32 of the tube 22 will both have positive potentialapplied thereto and saturation current will flow in the triode 22.However, no current can flow inthe triode 23 because negative potentialis applied to its anode. Likewise, no current can flow in the triode 24because positive potential is applied to its cathode.

The triode 25 has'negative potential applied to its cathode and would'be in condition to conduct current if the grid potential were abovecut-off value. However, at the instant assumed, the transformer winding44 applies negative voltage to the grid of the triode 25 andminimumcurrent flows therein unless the magnitude of the reference voltage issufficient to drive the tube 25 to cut-01f. Preferably, a large enoughvalue of reference voltage is chosen'so that the tubes 'will be drivenbeyond cut-off during negative half cycles of grid voltage. However,effective operation will be obtained in either case.

At the instant assumed, the discharge current through the tube 22 willpreponderate "over that through the tube 25 and current will flowthrough the load resistor 45 in such a direction that the terminal 39will be positive and the terminal 41 negative. At an instant electricaldegrees later, all of the polarities will be reversed and preponderatingcurrent will flow through the triode 23 to the output circuit, againapplying positive potential to the terminal 39 and negative potentialto'the terminal 4|.

When the input voltage is reversed in polarity with respect to thereference voltage, preponderating currents will flow alternately throughthe triodes 24 and 25 instead of through the triodes 22 and 23, thuscausing negative potential to be applied to the output terminal 39 andpositive potential to the output terminal 4|. Thus, the polarity of thepotential between the output terminals 39 and 44 is indicative of thephase relationship between the input voltages at the terminals l4 andHi.

In case of phase lag or phase lead between the input voltages, currentwill flow for a portion of a cycle through the triodes 22 and 23 and forthe remaining portion of a cycle through the tubes 24 and 25.Consequently, the potential difference between the terminals 39 and 41will be less than for phase coincidence of input voltages; and abalanced current condition will take place with zero output potentialdifference when the input voltages are in phase quadrature.

For the purpose of smoothing the output voltage, a load resistor 45,by-passed by a filter condenser 46, or a filter condenser 46 alone maybe connected between the output terminals 39 and 41.

For protecting the triodes grid-current limiting resistors 41 arepreferably provided. These serve also to make the output of the circuitsubstantially independent of variation in peak amplitude of thereference voltage if the reference voltage is applied at the terminalsI6. The output will then depend chiefly upon the phase and amplitude ofthe signal voltage applied to the terminals I4.

In the arrangement of Fig. 1 the reference voltage applied to theterminals I6 may be sinusoidal. Peaked wave reference voltage may alsobe employed; however, in case a peaked wave is employed the precisioneffect of the peaked wave form. is best obtained by introducing anegative bias in the grid circuits of the vacuum tubes. For

example, as illustrated in Fig.2, bias batteries 48, 49 and 50 may beprovided. A common bias battery 48 may be utilized for the grids 32 and33 if desired, but obviously separate bias batteries 49 and'50 will berequired for the triode units 24 and 25. A peak wave reference voltagesource (not shown), with a wave form as illustrated in Fig. 5, isconnected to the reference voltage terminals 16 of Fig. 2. Thebatteries48, 49 and 50 are selected to have sufficient voltage to biasthe grids beyond cut-01f and the relationship between the peak voltageof the reference voltage source and the bias voltages may be such thatthe tubes become conducting only during the brief interval of theuppermost peak value of the reference voltage. Grid resistors are thenunnecessary forprotecting the tubes,

In the arrangement of Fig. 2, therefore, the

amount of current flowing through each vacuum tube does not representthe area under the por-.

tion of the positive half cycle of the signal voltage occurring duringthe positive half cycle of the reference voltage.

In the arrangement of Fig. 2 the current flow- "is conducting :depends"upon the linstantaneous value of the input signal at the instant-thatthe reference voltageis applid t'o thegriu of-the tube'inquestion In th-denser' 46 is charged to the instantaneous potential of'theinput-signal as illustrated in Figxdby the'points-' *5 2. During-thehalf cycles following the application of peaked reference voltage, ftheoutput voltage 'Ofthe' condenser-E6 "falls along the exponentialfcurvesfl. -In--Fig.-'6 the inputsis'hal is representedbythe dotted sinusoidalcurve 354; The first ipertion jof the --output curveshcwn indull linesin Fig.6 represents the "output voltage with "phase coin; cidencebetween "the'inputfsignal and the "reference 'voltag'ejas representedby'fthe "portion '55 of the graph or Fig. 4. "in'the event of phasereversal 'of thqinfili't signal, whichcon'dition is repre} sented byportion 56, G flFi'g; '4, a difierent-pair of tubes becomes conductingand current flows-Blur ing negative half cycles of the input signalinstead of the positive half cycles, thus'produ-cing negative peaks 5?"and intervening exponential voltagedecay curves 58. It will beunderstood that, 'for some intermediate values of. phase angle otherthan phase coincidence or phase opposition between the input "signalan'dthe reference voltage, the tubes will become conducting at some inputvoltage other than the maximum-instantaneo'us value and 'the condenser46 will be charged'to a-smaller valuethan shown in 'Fig. 6 with ama'gI-iitude and polarity-depending"upon theph'ase angle. v

The use of a peaked wave-reference voltage lessens the amount oifilterin-grequired"andiincreases the-rapidity of response of thecircuittc changes inmagnitude and phase of the'si'gnal voltage.

If it is desired to avoid the use of bias batteries such as thebatteries 48, 49 and 50, the action of the circuit of Fig. 2 may beobtained by utilizing by-passed grid bias resistors 6| as shown in Fig.3 in the grid circuits of each of the triodes. Each resistor BI isshunted by a condenser 62 of sufficient capacitance to produce a timeconstant with the resistor which is long in comparison with thefrequency of the signal voltage and the reference voltage.

I have herein shown and particularly described certain embodiments of myinvention and certain methods of operation embraced therein for thepurpose of explaining its principle of operation and showing itsapplication, but it will be obvious to those skilled in the art thatmany modifications and variations are possible and I aim therefore tocover all such modifications and variations as fall within the scope ofmy invention, which is defined in the appended claims.

What is claimed is:

1. Phase responsive apparatus comprising, in combination, a pair ofinput transformers, a pair of unilateral current-controlling deviceshaving voltage responsive control elements, a second pair ofcurrent-controlling devices having voltage responsive control elements,and a pair of output terminals, one of said transformers having acenter-tapped secondary Winding, one pair of current-controlling devicesbeing connected in series opposing relation across said secondarywinding with their junction terminal connected to one of said outputterminals and the center tap of said secondary winding connected to thesecond output terminal, the second pair of current-conilfitG'fVaLl 6fti-me the ccmtrollingdevices being connected in serie's opposingreiati'on across said secondary windingwith their junction terminalconnected to 'said iirs'tmentioned junctionterminal, one-pair orcurrent-'- controlling devic'es both being arranged i to p'ermit'current fi'ow toward their junction terminal, and theother pair ofcurrent-controlling device's both being arr'ange'd'to perm-it currentiiowaway from-their ju'nction terminal, 'the second trans-'- former-h'aving four windings each of which-is connected Ltd the controlelement of one of said current-controlling devices, the relative phasingof said four windings being-suchthat the voltages appliedf to thecontrol elements of*each-pair of current-controlling devices haveopposite polari ties at any given instantq-andthat the voltages appliedto the cont'rol elements of current com trollin devices connectedto thesame end-of said center-tapped secondary winding have like polarity atany-given instant. 7

2. Phase responsive apparatus comprising-fin combination iirstand secondinput transformers each having two secondary windings, first and secondconnections from-two =altern'ating-sources to be compared L in phase for energizing said first' and second transformers, respectively, apairof unilateral"current-'controllingdevices havingvolt age 'responsivecontrol elements, anda pair of cut-f put termiiials, saidcurrent-controlling devices; being connected in series-opposing relationto the series-connected secondary windings of one of said transformersand having their junction terminal f connected 'to one of said I output-terminals,-said'secondary windings having theiriun'c i tionterminalconnected to the other of said out; put terminalaand thesecondarywindingsof the second transformer each being so phased andconnected -to' one of the control elements of saidcurrent-controllingdevices that potentials of bp'' posite polarities areapplied to said control elements at any given instant.

3. Phase responsive apparatus comprising, in combination, a pair ofelectric discharge devices each having an anode, a cathode, and acontrol electrode, first and second pairs of terminals to which voltagesmay be applied which are to be compared in phase, means for couplingsaid discharge devices in series opposition to one of said pairs ofterminals, means for coupling the control electrodes of said devices tothe second of said pairs of terminals, potentials of opposite polaritiesbeing applied to the control electrodes, and an output circuit withmeans connecting said discharge devices in parallel relation to saidoutput circuit.

4. Phase responsive apparatus comprising in combination, first andsecond pairs of electric discharge devices each havin an anode, acathode and a control electrode, means for applying to said first pairof discharge devices, in series opposition, me of two voltages to becompared in phase, means for applying between the control electrodes ofsaid first pair of discharge devices the second of said two voltages, anoutput circuit with means connecting said first pair of dischargedevices in arallel relation to said output circuit, means ior applyingto said second pair of discharge devices, also in series opposition, thefirst of said two voltages, means for applying between the controlelectrodes of said second pair of said discharge devices the second ofsaid two voltages, and means for connecting said second pair ofdischarge devices in parallel relation to said output circuit, each inopposing relation to the corre-- spending device of said first pair.

5. Phase responsive apparatus comprising in combination, first, second,third and fourth electric discharge devices, each having an anode, acathode and a control electrode, first and second pairs of inputterminals to which voltages may be applied which are to be compared inphase, means for coupling the first and second discharge devices to saidfirst pair of terminals in series opposition with their anodes connectedtogether, means for coupling the control electrodes of the first andsecond discharge devices in opposite relation to the second pair ofterminals, means for coupling the third and fourth discharge devices tothe first pair of terminals in series opposition with their cathodesconnected together, means for coupling the control electrodes of thethird and fourth devices in opposite relation to the second pair ofterminals, and an output circuit with means for connecting saiddischarge devices in parallel relation to said output circuit.

6. Apparatus as in claim with peaking means interposed in the couplingsbetween the second pair of terminals and the control electrodes.

7. Apparatus responsive to the amplitude of a signal voltage and to itsphase in relation to a reference voltage comprising in combination, apair of electric discharge devices each having an anode, a cathode and acontrol electrode, means for biasing said control electrodes beyondcut-ofl, means for applying the reference voltage to the controlelectrodes of the discharge devices, an output circuit to which saiddischarge devices are connected in parallel relation, and means forapplying the signal Voltage with one polarity to the anode of one ofsaid discharge devices and with the opposite polarity to the anode ofthe other discharge device, the magnitude of the reference voltage beingsufficient to overcome the cut-off bias and make the output relativelyunresponsive 8 to variations in magnitude of the reference voltage butresponsive to magnitude and phase of the signal voltage.

8. Phase-responsive apparatus comprising in combination: first andsecond electron discharge devices each having an anode, a cathode, and acontrol electrode; means for applying to said discharge devices firstand second voltages to be compared in phase; an output circuit havingfirst and second terminals; direct connections from said first terminalto the anode of said first discharge device and the cathode of saidsecond discharge device; connections from said second terminal to thecathode of said first discharge device and the anode of said seconddischarge device; means for applying said first voltage to the anodes ofsaid discharge devices with opposite polarities; and means for applyingsaid second voltage to the control electrodes of said discharge deviceswith the same polarity, said means comprising an inductive couplingbetween said control electrodes.

RAWLEY D. McCOY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,986,627 Edwards et a1 Jan, 1,1935 2,113,220 Power Apr. 5, 1938 2,141,937 Schroter Dec, 27, 19282,225,348 -Mikelson Dec. 17, 1940 2,301,635 Norton Nov. 10, 19422,318,197 Clark May 4, 1943 2,281,995 Purington May 5, 1942 2,335,265Dodington Nov. 30, 1943 2,242,946 Faulk May 20, 1941

